CAIRO, Sept. 10 (UPI) — Egyptian authorities investigated Italian student Giulio Regeni two weeks before he was found dead, but determined he posed no threat to national security, investigators said.

Egypt’s top prosecutor, Nabil Sadek, said the Egyptian police launched an investigation into Regeni, a Cambridge University doctoral student who was in the country researching labor movements. Investigators questioned Regeni’s research into Egyptian street vendor trade unions but quickly found his work was “no concern to national security.”

Regeni was reported missing on Jan. 25 and his body, which showed signs of torture, was found near Cairo on Feb. 3.

Egyptian authorities initially said Regeni was killed by a criminal gang, critics believe that theory to be unlikely. They also suggested Regeni may have been killed in a car accident, though an autopsy concluded that Regeni was likely beaten with “fists, batons, and hammers.”

In April the Italian ambassador to Egypt was recalled to protest Egypt’s handling of the case.